GB 2433265 A (DEREK LOWE) discloses a low toxicity fuel for four-stroke engines, wherein the fuel includes 80-99% ethanol and 1-20% volatile hydrocarbon fractions that are soluble in ethanol. The volatile hydrocarbon fractions are described as being advantageously selected from the group comprising pentane, iso-pentane, butane, iso-butane, propane and combinations thereof.
WO 2004/050803 A1 (GREG BINIONS) discloses a liquid fuel composition comprising 10-80 vol % of a first component comprising at least two aliphatic organic non-hydrocarbon compounds; 20-65 vol % of a second component comprising at least one hydrocarbon and having an aromatic content of less than 15 vol % of the total second component; 1-35 vol % of a third component which comprises an oxygenate; 0.01 to 20 vol % water, wherein at least one compound in the fuel composition is miscible with both water and hydrocarbons to provide a single phase composition. Preferred compounds for use in the first component are disclosed as including ethyl alcohol, propyl alcohol, butyl alcohol, octyl alcohol, butanone, methyl isobutyl ketone, ethyl acetate, isopropyl alcohol and isobutyl alcohol. Light naphthas and some types of gasoline as disclosed as being suitable for the second component, and it is also disclosed straight chain saturated or unsaturated hydrocarbons whose number of carbon atoms is 9 or less may be used in place of all or a part of a low aromatic naphtha for the second component. Ethers which generally have at least two hydrocarbon groups which each have seven, preferably six, or less carbon atoms in the hydrocarbon chain are disclosed as being suitable compounds for the third component, with methylcyclopentadienyl manganese tricarbonyl (MMT), methyl tertiary butyl ether (MTBE), tertiary amyl methyl ether (TAME), ethyl tertiary-butyl ether (ETBE) and dibutyl ether are described as being preferred ethers.
WO 2004/055134 A2 (ALAN EASTMAN ET AL.) discloses a combustible fuel comprising:
(A) an alcohol component in the range of about 55% to about 70% by weight;
(B) a naphtha component in the range of about 30% to about 45% by weight.
WO 2004/055134 A2 states “The term naphtha (or gasoline) as used herein can refer to hydrocarbon compositions. These hydrocarbon compositions include mixtures of hydrocarbons with an atmospheric-pressure boiling range of approximately 40-205° C. (100-400° F.), and can be comprised of alkanes, olefins, naphthalenes, aromatics, etc.”
WO 2006/031319 A2 (CONOCOPHILIPS) discloses the use of Fischer-Tropsch naphtha as a denaturant, in particular as a denaturant for ethanol. The denatured ethanol of WO 2006/031319 A2 can then be blended with gasoline to provide a fuel composition. In the examples of WO 2006/031319 A2, example 2 combines about 5.0 gallon of 200 proof ethanol with about 0.1 gallons of Fischer-Tropsch naphtha to form a denatured alcohol. The denatured alcohol of example 2 is then blended with about 51.0 gallons of gasoline; the resulting gasoline is suitable for use in automobiles.
Nowhere in GB 2433265 A, WO 2004/050803 A1 or WO 2004/055134 A2 is the use of Fischer-Tropsch derived naphtha in fuel compositions disclosed.
The distillation properties of Fischer-Tropsch derived naphtha components are comparable to those of gasoline. Despite this, Fischer-Tropsch derived naphtha components have not been generally considered suitable for use directly in gasoline fuel compositions because their octane numbers are too low.